<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
        .container {
            display: flex;
            flex-direction: column;
        }
        .sidebar {
            background-color: lightgray;
            padding: 10px;
        }

        .main-content {
            background-color: lightblue;
        }
        /*? 屏幕改变时改变布局*/
        @media screen and (min-width: 768px) {
            .container {
                flex-direction: row;
            }
            .sidebar {
                flex-basis: 200px;
            }
            .main-content {
                flex-grow: 1;
                margin: 0 10px;
            }
        }
    </style>
</head>
<body>
<div class="container">
    <div class="sidebar">Sidebar</div>
    <div class="main-content">Main Content</div>
    <div class="sidebar">Sidebar</div>
</div>
</body>
</html>
